1. Field of the Invention
The invention relates to toilet tank trip lever assemblies that allow the user to choose between selected flush volumes.
2. Description of the Art
Due to increasing population and limited water supply, conservation of water is becoming important. A significant source of water consumption is the water used in flushing toilets. The art has recognized that in some cases a full volume flush is not required to clean out a toilet bowl (e.g., urine and small amounts of paper only). Thus, many toilets that are designed to remove heavy amounts of feces and paper will waste water when faced with much lighter loads. The art has therefore developed toilet flushing mechanisms that use less water during certain flush cycles selected by the user.
In some of these dual flush mechanisms, the user selects one of two flush volumes by operating one of two flush handles on the toilet tank. To facilitate retrofitting existing toilets, and to minimize costs for new tanks, it is important that the control mechanism use only a single handle hole in the toilet tank. Accordingly, control mechanisms have been developed which employ two handles mounted to a single shaft or to concentric shafts which extend through the single handle mounting hole of a conventional toilet tank. Internally, the shafts are attached to one or more members which open the flush valve for a full flush or a partial flush respectively. See, for example, U.S. Pat. No. 4,837,867.
More widespread adoption of such systems has been deterred in part because of cost, complexity, difficulty in installation, concerns about reliability and/or other problems. For example, there has been difficulty in developing breakage resistant systems that use plastic components.